The present invention relates to a television (TV) apparatus that uses removable memory cards to enhance the quality and availability of interactive television services.
Interactive services to digital television and set-top-box apparatus have been in operation for a number of years. These generally allocate volatile memory (i.e. where memory contents are lost when power is withdrawn), usually dynamic random access memory (DRAM), within the apparatus to temporary storage of an interactive television service content such as games, news or TV listings. Often, a content item is broadcast alongside a digital television service and shares the same multiplex. In which case, a cue for allowing selection of the content item may be displayed over a television programme in a format or style specific to the item. Users may invoke an item of content belonging to an interactive service by selecting a key on a remote control that corresponds to the cue displayed on the screen of the apparatus. The item is downloaded to the storage area from a continuously broadcast data “carousel” and executed.
The downloaded item may be split into multiple objects, some comprising executable application software, and others comprising data objects including graphics, video, text and sound objects. Each object may reference other objects. Objects typically remain in storage until the user selects a cue corresponding to another content item, whereupon the previous item is either wholly or partially overwritten by the new item. Hence, if the user were to select the original item again, its objects must again be downloaded. A problem with this approach is that a user experiences an undesired delay between selecting the cue and the item appearing on the television screen while the item's objects are downloaded to the apparatus. Also, the broadcaster must broadcast repetitively each item, usually many hundreds or thousands of times during a day. This is wasteful of bandwidth and is costly to terrestrial broadcasters whose bandwidth is often limited compared to those of cable and satellite counterparts.
Another approach is to broadcast content items only a small number of times, such as once or twice per day, and to cause the apparatus to power up and to store them in non-volatile memory (a common form being referred to as “flash” memory). This reduces bandwidth wastage and makes selection of items more responsive because the items do not have to be loaded from a data carousel in real time. However, given that volume television receiving apparatus are cost sensitive and that their main purpose is for watching television, a disadvantage of this approach is that it loads incremental memory costs onto the apparatus. Alternatively, items may be broadcast a small number of times per day and stored in DRAM only. This has the advantage of reducing materials costs and improving responsiveness to user selection of cues but requires the apparatus to be powered up or in low power standby in order not to lose the stored items.